Housing structure for a turbomachine, turbomachine and method for cooling a housing portion of a housing structure of a turbomachine

Abstract

The present invention relates to a housing structure for a turbomachine, a turbomachine, and a method for cooling a housing portion of a housing structure of a turbomachine, wherein the housing structure has an outer housing wall, which is formed by at least one housing part, and an inner wall, wherein the inner wall is arranged in the radial direction inside of the housing wall and spaced apart from the housing wall and is designed to bound the main flow channel, at least partially, wherein the housing structure comprises a cooling air channel for cooling a housing portion to be cooled, and has an upstream end and a downstream end, wherein the cooling air channel extends, at least partially, between the housing wall and the inner wall.

What is claimed is: 
     
       1. A housing structure for a turbomachine, wherein the housing structure surrounds annularly, at least partially, a main flow channel of the turbomachine, in which rotating blades and guide vanes are arranged, and to delimit the turbomachine with respect to the surroundings, wherein the housing structure comprises an outer housing wall, which is formed by at least one housing part, and an inner wall, and at least one cooling air channel, which extends, at least partially, in a volume between the housing wall and the inner wall, for cooling a housing portion to be cooled of the housing wall,
 wherein the housing wall delimits the turbomachine with respect to the surroundings, 
 wherein the inner wall is arranged in a radial direction inside of the housing wall and spaced apart from the housing wall in the radial direction, and bounds, at least partially, the main flow channel together with the rotating blades and the guide vanes arranged therein, 
 wherein, in relation to a main flow direction, with which a main flow passes through the main flow channel, the housing portion to be cooled has an upstream end and a downstream end, 
 wherein the cooling air channel has a cooling air channel inlet for feeding cooling air into the cooling air channel and a cooling air channel outlet for discharging cooling air from the cooling air channel, 
 wherein the cooling air channel has a first portion and a second portion, the cooling air channel is configured and arranged such that cooling air that is conveyed to the cooling air channel via the cooling air channel inlet flows in the direction of the upstream end of the housing portion to be cooled, 
 wherein the cooling air channel inlet is arranged in a region of the downstream end of the housing portion to be cooled or is arranged downstream of said end, 
 wherein the housing structure has at least one intermediate wall, which extends, at least partially, in the axial direction and, at least partially, in a peripheral direction and is arranged in the radial direction between the housing wall and the inner wall, and 
 wherein the cooling air channel is bounded inwardly in the second portion in the radial direction by an outer surface of a second intermediate wall, which extends, at least partially, in the axial direction and is arranged in the radial direction between the first intermediate wall and the inner wall. 
 
     
     
       2. The housing structure according to  claim 1 , wherein the cooling air channel outlet is also arranged in the region of the downstream end of the housing portion to be cooled, at the downstream end of the housing portion to be cooled, or downstream of the downstream end of the housing portion to be cooled. 
     
     
       3. The housing structure according to  claim 1 , wherein the cooling air channel, is configured and arranged so that cooling air that is conveyed to the cooling air channel via the cooling air channel inlet flows in the first portion in the direction of the upstream end of the housing portion to be cooled, and flows in the second portion in the direction of the downstream end of the housing portion to be cooled, wherein a cooling air flow is diverted in a transition region of the cooling air flow from the first portion to the second portion by 180°. 
     
     
       4. The housing structure according to  claim 1 , wherein the cooling air channel in the first portion is bounded in the radial direction by an inner surface of the housing portion to be cooled of the housing wall and by an outer surface of an intermediate wall, which extends, at least partially, in the axial direction and is arranged in the radial direction between the housing wall and the inner wall. 
     
     
       5. The housing structure according to  claim 4 ,
 wherein the first intermediate wall is disposed at a downstream end of the housing wall downstream of the cooling air channel inlet, against the inner surface of the housing wall with a defined contact force, for axial bounding of the cooling air channel downstream for axial bounding of the first portion of the cooling air channel downstream. 
 
     
     
       6. The housing structure according to  claim 1 , wherein the cooling air channel is bounded outwardly in the second portion in the radial direction by an inner surface of the first intermediate wall. 
     
     
       7. The housing structure according to  claim 1 , wherein the second intermediate wall is applied by its upstream end in the region of the upstream end of the housing wall, upstream of a diversion in the cooling air channel, against the inner surface of the housing wall, with a defined contact force, for axial bounding of the cooling air channel upstream, for axial bounding of the second portion of the cooling air channel upstream. 
     
     
       8. The housing structure according to  claim 1 , wherein the cooling air channel outlet is formed by an opening between the first intermediate wall and the second intermediate wall. 
     
     
       9. The housing structure according to  claim 1 , wherein at least one sealing element, which extends at least partially in the axial direction and at least partially in the peripheral direction, is arranged radially between the housing wall and the inner wall, wherein the sealing element is arranged in the radial direction between an innermost intermediate wall, which bounds the cooling air channel, and the inner wall. 
     
     
       10. The housing structure according to  claim 1 , wherein the housing structure is configured and arranged as part of a low-pressure turbine. 
     
     
       11. The housing structure according to  claim 10 , wherein the turbomachine has a rotor stage with rotating blades and a stator stage with guide vanes, which is arranged downstream of the rotor stage, wherein the housing portion to be cooled of the housing structure surrounds at least the rotor stage, at least partially, radially, wherein the turbomachine is configured and arranged so that cooling air is conveyed to the cooling air channel from the stator stage arranged downstream with respect to the rotor stage from radially outside of the guide vanes of the downstream stator stage at least partially opposite to a main flow direction of a main flow in the main flow channel. 
     
     
       12. The housing structure according to  claim 10  wherein the inner wall of the housing structure forms a discharge gap at its downstream end with at least one guide vane of the stator stage that is adjacent to the rotor stage, by way of which the cooling air that is discharged from the cooling air channel can be discharged into the main flow channel together with a hot leakage flow that, owing to leakages, is discharged from the main flow channel. 
     
     
       13. The housing structure according to  claim 11 , wherein the cooling air is conveyed to the cooling air channel of the housing structure, the housing portion of which to be cooled surrounds, at least partially, the rotor stage arranged upstream of the stator stage, by way of the cooling air channel inlet from a region radially outside of the guide vanes of the stator stage, wherein, for this purpose, the turbomachine is operable such that a cooling air pressure in this region is greater than a discharge pressure of a flow in the region of the cooling air channel outlet.